pci_find_cap_method(): limit number of iterations for finding a capability

[kib]

Summary

Powered down device might return 0xff of extended config registers
reads, causing loop.

PR:     283815

[imp]

Any chance 0x40 has a constant already defined for it?

[kib]

In D48348#1102529, @imp wrote:

Any chance 0x40 has a constant already defined for it?

I tried to explain it in the comment above, your suggestion is welcomed. It should be the size of the fixed PCI header of some type.